Thin films, structures having thin films, and methods of forming thin films

ABSTRACT

The invention described herein relates to new titanium-comprising materials which can be utilized for forming titanium alloy barrier layers for Cu applications. Titanium alloy sputtering targets can be reactively sputtered in a nitrogen-comprising sputtering gas atmosphere to from titanium alloy nitride film, or alternatively in a nitrogen-comprising and oxygen-comprising atmosphere to form titanium alloy oxygen nitrogen thin film. The thin films formed in accordance with the present invention can contain a non-columnar grain structure, low electrical resistivity, high chemical stability, and barrier layer properties comparable or exceeding those of TaN.

TECHNICAL FIELD

The invention pertains to titanium alloy thin films with improved copperdiffusion barrier properties. The invention also pertains to diffusionprotected surfaces and structures containing titanium alloy thin films.The invention additionally pertains to methods of forming barrier layersand methods of forming structures containing barrier layers.

BACKGROUND OF THE INVENTION

Integrated circuit interconnect technology is changing from aluminumsubtractive processes to copper dual damascene processes. The shift fromaluminum and its alloys to copper and its alloys is causing new barrierlayer materials, specifically TaN, to be developed. TiN films, whichwere used in aluminum technologies, could be formed by, for example,reactively sputtering a titanium target in a nitrogen-comprisingsputtering gas atmosphere. TiN films are reportedly poor barrier layersrelative to copper in comparison to TaN.

The problems associated with TiN barrier layers are described withreference to FIGS. 1 and 2. Specifically, FIG. 1 illustrates a preferredbarrier layer construction, and FIG. 2 illustrates problems associatedwith TiN barrier layers.

Referring initially to FIG. 1, a semiconductor wafer fragment 10 isillustrated. Wafer fragment 10 comprises a substrate 12 which cancomprise, for example, monocrystalline silicon. To aid in interpretationof the claims that follow, the terms “semiconductive substrate” and“semiconductor substrate” are defined to mean any constructioncomprising semiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove.

An insulative layer 14 is formed over substrate 12. Insulative layer 14can comprise, for example, silicon dioxide or borophosphosilicate glass(BPSG). Alternatively, layer 14 can comprise fluorinated silicon dioxidehaving a dielectric constant less than or equal to 3.7, or a so-called“low-k” dielectric material. In particular embodiments, layer 14 cancomprise an insulative material having a dielectric constant less thanor equal to 3.0.

A barrier layer 16 is formed to extend within a trench in insulativematerial 14, and a copper-containing seed layer 18 is formed on barrierlayer 16. Copper-containing seed layer 18 can be formed by, for example,sputter deposition from a high purity copper target, with the term “highpurity” referring to a target having at least 99.995% purity (i.e., 4N5purity). A copper-containing material 20 is formed overcopper-containing seed layer 18, and can be formed by, for example,electrochemical deposition onto seed layer 18. Copper-containingmaterial 20 and seed layer 18 can together be referred to as acopper-based layer or copper-based mass.

Barrier layer 16 is provided to prevent copper diffusion from materials18 and 20 into insulative material 14. It has been reported that priorart titanium materials are not suitable as barrier layers for preventingdiffusion of copper. Problems associated with prior arttitanium-comprising materials are described with reference to FIG. 2,which shows the construction 10 of FIG. 1, but which is modified toillustrate specific problems that can occur if either pure titanium ortitanium nitride are utilized as barrier layer 16. Specifically, FIG. 2shows channels 22 extending through barrier layer 16. Channels 22 canresult from columnar grain growth associated with the titanium materialsof barrier layer 16. Channels 22 effectively provide paths for copperdiffusion through a titanium-comprising barrier layer 16 and intoinsulative material 14. The columnar grain growth can occur duringformation of a Ti or TiN layer 16, or during high temperature processingsubsequent to the deposition. Specifically, it is found that even whenprior art titanium materials are deposited without columnar grain, thematerials can fail at temperatures in excess of 450° C.

In an effort to avoid the problems described with reference to FIG. 2,there has been a development of non-titanium barrier materials fordiffusion layer 16. Among the materials which have been developed istantalum nitride (TaN). It is found that TaN can have a close tonanometer-sized grain structure and good chemical stability as a barrierlayer for preventing copper diffusion. However, a difficulty associatedwith TaN is that the high cost of tantalum can make it difficult toeconomically incorporate TaN layers into semiconductor fabricationprocesses. Alternatively, we have found that many titanium alloys canhave superior mechanical properties compared to tantalum; both in thesputtering target and sputtered film; thus making them suitable forhigh-power applications.

Titanium alloys are a lower cost material than tantalum. Accordingly, itis possible to reduce materials cost for the microelectronics industryrelative to utilization of copper interconnect technology if methodologycould be developed for utilizing titanium-comprising materials, insteadof tantalum-comprising materials, as barrier layers for inhibitingcopper diffusion. It is therefore desirable to develop newtitanium-comprising materials which are suitable as barrier layers forimpeding or preventing copper diffusion. The titanium comprisingmaterials can be of any purity, but are preferably high purity; with theterm “high purity” referring to a target having at least 99.95% purity(i.e., 3N5 purity).

SUMMARY OF THE INVENTION

The invention described herein relates to new titanium-comprisingmaterials which can be utilized for forming titanium alloy sputteringtargets. These sputtering targets can be used to replacetantalum-comprising targets due to their high-strength and resultingfilm properties. Specifically, in certain embodiments, the titaniumalloy, sputtering targets can be used to form barrier layers for Cuapplications. The titanium alloy sputtering targets can be reactivelysputtered in a nitrogen-comprising sputtering gas atmosphere to formtitanium alloy nitride film, or alternatively. in a nitrogen-comprisingand oxygen-comprising atmosphere to form titanium alloy oxygen nitrogenthin film. The thin films formed in accordance with the presentinvention can contain a non-columnar grain structure, low electricalresistivity, high chemical stability, and barrier layer propertiescomparable or exceeding those of TaN. Further, the titanium alloysputtering target materials for production if thin films in accordancewith the present invention are more cost-effective for'semiconductorapplications than are high-purity tantalum materials.

In one aspect, the invention encompasses a thin film comprisingzirconium and nitrogen. At least a portion of the thin film has anon-columnar grain structure.

In one aspect, the invention encompasses a copper barrier film that hasa first portion which comprises a non-columnar grain structure and has asecond portion that contains columnar grain structure. The film has asubstantial absence of amorphous phase material.

In one aspect, the invention encompasses a structure which includes asilicon substrate. The structure has an insulative material over thesubstrate and a barrier layer comprising (TiZr)_(x)N_(z) over theinsulative material. The barrier layer has a substantial absence ofamorphous structure and at least a portion of the barrier layer containsnon-columnar grain structure. The structure also has a layer containinga metal over the barrier layer.

In one aspect, the invention encompasses a method of forming a barrierlayer which includes providing a substrate which contains a material tobe protected. A titanium material target is provided and material fromthe target is ablated onto the substrate in the presence of an Ar/N₂plasma, at a deposition power of from about 1 kW to about 9 kW. Theablated material forms a barrier layer containing titanium and nitrogenwhich has a substantially uniform thickness over at least a portion ofthe material to be protected.

In one aspect, the invention encompasses a method of inhibiting copperdiffusion into a substrate. A first layer comprising titanium and one ormore alloying elements is formed over the substrate. A group ofappropriate alloying elements includes Al, Ba, Be, Ca, Ce, Cs, Hf, La,Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P, S, Sm, Gd,Dy, Zr, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta. A copper-based layer is thenformed over the first layer and separated from the substrate by thefirst layer. The first layer inhibits copper diffusion from thecopper-based layer to the substrate.

For purposes of interpreting this disclosure and the claims that follow,a “titanium-based” material is defined as a material in which titaniumis a majority element, and an “alloying element” is defined as anelement that is not a majority element in a particular material. A“majority element” is defined as an element which is present in largerconcentration than any other element of a material. A majority elementcan be a predominate element of a material, but can also be present asless than 50% of a material. For instance, titanium can be a majorityelement of a material in which the titanium is present to only 30%,provided that no other element is present in the material to aconcentration of greater than or equal to 30%. The other elementspresent to concentrations of less than or equal to 30% would be“alloying elements.” . Frequently, titanium-based materials describedherein will contain alloying elements at concentrations of from 0.001atom % to 50 atom %. The percentages and concentrations referred toherein are atom percentages and concentrations, except, of course, forany concentrations and percentages specifically indicated to be otherthan atom percentages or concentrations.

Additionally, for purposes of interpreting this disclosure and theclaims that follow a “copper-based” material is defined as a material inwhich copper is the majority element.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of a prior artsemiconductor wafer fragment illustrating a conductive copper materialseparated from an insulative material by a barrier layer.

FIG. 2 is a view of the FIG. 1 prior art wafer fragment illustratingproblems which can occur when utilizing prior art Ti-containingmaterials as the barrier layer.

FIG. 3 is a diagrammatic, cross-sectional view of a semiconductor waferfragment at a preliminary step of a method of the present invention.

FIG. 4 is a view of the FIG. 3 wafer fragment shown at a processing stepsubsequent to that of FIG. 3.

FIG. 5 shows the step coverage of a (TiZr)_(x)N_(z) liner (Panel A) andthe step coverage of a (TiZr)_(x)N_(z) liner plus a copper seed coat(Panel B).

FIG. 6 is a view of the FIG. 3 wafer fragment shown at a processing stepsubsequent to that of FIG. 4.

FIG. 7 is a view of the FIG. 3 wafer fragment shown at a processing stepsubsequent to that of FIG. 6.

FIG. 8. is a chart showing improvements in mechanical properties ofTi—Zr alloys in comparison to prior art Ta.

FIG. 9 is a graph illustrating a Rutherford Back-scattering Spectroscopy(RBS) profile of as-deposited Ti_(0.45)Zr_(0.024)N_(0.52).

FIG. 10 is a graph illustrating a Rutherford Back-scatteringSpectroscopy profile Ti_(0.45)Zr_(0.024)N_(0.52) after vacuum annealingfor 1 hour at from 450° C. to 700° C.

FIG. 11 is a graph illustrating a Rutherford Back-scatteringSpectroscopy profile of a TiZrN thin film after stripping Cu layer froma wafer. The TiZrN thin film and Cu layer being initially part of astructure formed in accordance with an exemplary method of the presentinvention. The illustrated data shows no apparent diffusion of Cu intothe TiZrN layer after 5 hours at 700° C.

FIG. 12 shows a SEM microscopy image of a TaN film (Panel A) and a(TiZr)_(x)N_(z) film deposited at 400° C. with 6.5 kW power in an Ar/N₂plasma.

FIG. 13 shows a cross sectional TEM image of a 5 nm (TiZr)_(x)N_(z)barrier layer after annealing for 1 hour at 650° C.

FIG. 14 is a graph illustrating the electrical resistivity as a functionof deposition power for TaN and (TiZr)_(x)N_(z) films deposited at 400°C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are described withreference to FIGS. 3-7. Referring initially to FIG. 3, a semiconductorwafer fragment 50 is illustrated. Wafer fragment 50 comprises asemiconductive material substrate 52, such as, for example,monocrystalline silicon. An insulative material 54 is formed oversubstrate 52, and an opening 56 is formed into insulative material 54.Materials 52 and 54 can comprise the same materials as described withreference to the prior art for materials 12 and 14, respectively. Inparticular applications, material 54 can comprise an organic or aninorganic low-k dielectric material having a k value of less than orequal to about 2.6. Examples of such materials having k values of lessthan or equal to about 2.6 include GX-3, HOSP, and NANOGLASS® E(Honeywell International. Inc., Morristown, N.J.), although theinvention encompasses use of other dielectric materials having k valuesin this range.

Opening 56 can comprise, for example, a trench for formation of copperin a dual damascene process. Opening 56 can comprises a sidewall surface55, and bottom surface 57. The dimensions of opening 56 are not limitedto specific values. In particular applications, opening 56 can have awidth of less or equal to about 350 nm and in some instances can be lessthan or equal to about 200 nm, or less than or equal to about 100 nm.Additionally, the aspect ratio (the ratio of the height relative to thewidth) of opening 56 is not limited to a particular value and can be,for example, greater than about 1. In some instances the aspect ratiocan be greater than or equal to about 4.

Referring to FIG. 4, a barrier layer 58 is formed over insulative, layer54 and within opening 56, and forms an interface 59 between insulativelayer 54 and barrier layer 58. In accordance with the present invention,barrier layer 58 comprises titanium, and is configured to impedediffusion from subsequently-formed copper-based layers into insulativematerial 54. In one aspect of the invention, barrier layer 58 comprisestitanium and one or more elements selected from the group consisting ofAl, Ba, Be, Ca, Ce, Cs, Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co,Ni, B, C, La, Pr, P, S, Sm, Gd, Dy, Zr, Ho, Er, Yb, W, Cr, Mo, Nb, andTa. Further, barrier layer 58 can consist essentially of the titaniumand one or more elements. Barrier layer 58 can also comprise one or bothof nitrogen and oxygen in addition to the Ti and the one or moreelements. Layer 58 can be considered as a film formed over substrate 54,and in particular embodiments can be considered as a liner of opening56. Layer 58 will have a thickness of from about 2 nanometers to about500 nanometers, and can specifically have a thickness of from about 2nanometers to about 50 nanometers, or can specifically have a thicknessof from about 2 nanometers to about 20 nanometers.

Factors that can be important in determining appropriate elements andatomic ratio of elements to form the titanium alloy materials of thepresent invention include: 1) differences in atomic size relative to Ti;2) standard electrode potential of the element; and 3) meltingtemperature of the element. For example, a difference in atomic size candisrupt a titanium lattice structure, and accordingly impede graingrowth within the lattice. A magnitude of difference in grain sizebetween the titanium and the other elements incorporated into barrierlayer 58 can affect the amount by which a lattice is disrupted, andaccordingly can influence an amount of grain growth occurring at varioustemperatures. It can therefore be preferable in some instances, toutilize elements having larger differences in size relative to titaniumthan atoms having less difference in size relative to titanium.

In particular aspects of the invention, it can be advantageous toutilize one or more elements having a standard electrode potential ofless than −1.0 V. Such elements can tend to diffuse toward interfaceregions of the barrier layer when exposed to thermal processing andthereby enhance the ability of the layer to inhibit or prevent diffusioninto the barrier. Additionally, diffusion of the elements having astandard electrode potential of less than −1.0 V toward interfaceregions of the barrier layer can enhance the ability of the barrierlayer to adhere to insulative materials. In some instances it can beadvantageous to provide one or more elements having a meltingtemperature of greater than about 2400° C. to the alloy. Due to therefractory characteristics of elements having a melting temperature ofgreater than about 2400° C., inclusion of such elements can stabilizethe titanium alloy.

In some applications, layer 58 can be a barrier for inhibiting orpreventing diffusion from a metallic material to a non-metallicmaterial. In an exemplary process, layer 58 is a barrier layer forpreventing diffusion from a conductive copper-based. material toinsulative material 54. In such embodiment, it can be preferred thatbarrier layer 58 be conductive to provide additional electron flowbeyond that provided by the conductive copper-based layer. In suchembodiments, it can be preferred that barrier layer 58 have anelectrical resistivity of equal to or less than 300 μΩ·cm.

An exemplary method of forming barrier layer 58 is to sputter depositlayer 58 from a target comprising titanium and one or more elements. Theone or more elements can be selected from the group consisting of Al,Ba, Be, Ca, Ce, Cs, Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B,C, La, Pr, P, S, Sm, Gd, Dy, Zr, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta. Theinvention encompasses deposition from a target that consists essentiallyof the titanium and the one or more elements. Also, the inventionencompasses embodiments wherein the target consists of the titanium andthe one or more elements.

An exemplary target can comprise at least 50 atom % titanium, and from0.001 atom % to 50 atom % of the one or more elements selected from thegroup consisting of Al, Ba, Be, Ca, Ce, Cs, Hf, La, Mg, Nd, Sc, Sr, Y,Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P, S, Sm, Gd, Dy, Zr, Ho, Er, Yb,W, Cr, Mo, Nb, and Ta. In other embodiments, the target can comprise atleast 90 atom % titanium, and from 0.001 atom % to 10 atom % of the oneor more elements. The invention also encompasses utilization of targetshaving an atomic ratio of Ti to the one or more elements of less than 1.

In particular aspects of the present invention, the target utilized forforming barrier layer 58 will comprise zirconium. The ratio of titaniumto zirconium comprised by the target is not limited to any particularvalue. Accordingly, Zr can be present in the target at from greater than0 atomic percent to less than 100 atomic percent. In particularapplications, the TiZr comprising target can also include one or moreadditional element selected from the group consisting of Al, Ba, Be, Ca,Ce, Cs, Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr,P, S, Sm, Gd, Dy, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta. In otherembodiments, the TiZr target can consist essentially of Ti and Zr. Theinvention also encompasses utilization of TiZr targets consisting of Tiand Zr.

A target utilized in methodology of the present invention can besputtered in an atmosphere such that only target materials are depositedin film 58, or alternatively can be sputtered in an atmosphere so thatmaterials from the atmosphere are deposited in barrier layer 58 togetherwith the materials from the target. For instance, the target can besputtered in an atmosphere comprising a nitrogen-containing component toform a barrier layer 58 that comprises nitrogen in addition to thematerials from the target. An exemplary nitrogen-containing component isdiatomic nitrogen (N₂). The deposition atmosphere can, in someinstances, additionally comprises Ar. The deposited thin film can bereferred to by the stoichiometry (TiQ)_(x)N_(z), with “Q” being a labelfor the one or more elements selected from the group consisting of Al,Ba, Be, Ca, Ce, Cs, Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B,C, La, Pr, P, S, Sm, Gd, Dy, Zr, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta, thatwere incorporated into the target. In particular processing, thematerial (TiQ)_(x)N_(z) will comprise x=0.40 to 0.60, and z=0.40 to0.60. For example, where a target consisting essentially of titanium andzirconium is utilized for sputtering in an atmosphere comprisingnitrogen, the resulting thin film can be(TiZr)_(0.40-0.60)N_(0.40-0.60), and in particular embodiments will be(TiZr)_(0.47-0.6)N_(0.4-0.53).

Another exemplary method of forming barrier layer 58 is to sputterdeposit the layer from a target comprising titanium and one or moreelements other than titanium in the presence of both anitrogen-comprising component and an oxygen-comprising component, toincorporate both nitrogen and oxygen into barrier layer 58. Suchprocessing can form a barrier layer having the stoichiometryTi_(x)Q_(y)N_(z)O_(w), with Q again referring to the elements selectedfrom the group consisting of Al, Ba, Be, Ca, Ce, Cs, Hf, La, Mg, Nd, Sc,Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P, S, Sm, Gd, Dy, Zr, Ho,Er, Yb, W, Cr, Mo, Nb, and Ta. The compound Ti_(x)Q_(y)N_(z)O_(w) cancomprise, for example, x=0.1 to 0.7, y=0.001 to 0.3, z=0.1 to 0.6, andw=0.0001 to 0.0010. The oxygen-containing component used to form theTi_(x)Q_(y)N_(z)O_(w), can be, for example O₂.

There can be advantages to incorporating nitrogen and/or oxygen into abarrier layer 58, in that such incorporation can improve thehigh-temperature stability of the barrier layer relative to its abilityto exclude copper diffusion at high temperatures. The nitrogen and/oroxygen can, for example, disturb a Ti columnar grain structure and thusform a more equi-axed grain structure.

The electrically resistivity of barrier layer 58 can be influenced bydeposition conditions during ablation of material from the target ontoinsulative material 54. An appropriate deposition power can depend uponthe desired resistivity in layer 58, the particular composition of thedeposition target and the deposition method and conditions utilized.Where layer 58 comprises (TiZr)_(x)N_(z) an exemplary deposition powercan be from about 1 kW to about 9 kW. For instance, in applicationswhere layer 58 comprises (TiZr)_(x)N_(z) formed utilizing a depositionpower of about 2 kW, layer 58 can have a resistivity of about 69 μΩ·cm.Alternatively, the (TiZr)xN, layer can comprise a resistivity of about106 μΩ·cm when formed at a deposition power of about 8.6 kW.

A barrier layer 58 formed in accordance with the present invention cancomprise a mean grain size of less than or equal to 100 nanometers, andin particular processing can preferably comprise a mean grain size ofless than or equal to 10 nanometers. More preferably, the barrier layercan comprise a mean grain size of less than 1 nanometer. Further, thebarrier layer material can have sufficient stability so that the meangrain size remains less than or equal to 100 nanometers, and inparticular embodiments less than or equal to 10 nanometers or 1nanometer, after the film is exposed to 500° C. for 30 minutes in avacuum anneal.

The small mean grain size of the film 58 of the present invention canenable the film to better preclude copper diffusion than can prior arttitanium-containing films. Specifically, the prior arttitanium-containing films frequently would form large grain sizes atprocessing above 450° C., and accordingly would have the columnar-typedefects described above with reference to FIG. 2. Processing of thepresent invention can avoid formation of such defects, and accordinglycan enable better titanium-containing diffusion layers to be formed thancould be formed by prior art processing.

Where barrier layer 58 is deposited from a target comprising titaniumand zirconium according to the present invention, layer 58 can comprisethe same atomic ratio of titanium relative to zirconium as the target.Additionally, where additional metals are comprised by the target, layer58 can have the same atomic ratio of the additional elements relative tothe titanium and zirconium as was present in the target. Alternatively,barrier layer 58 can have an atomic ratio of titanium relative to theone or more additional elements that varies relative to thecorresponding target. In particular aspects of the invention, barrierlayer 58 can consist essentially of titanium, zirconium and nitrogen. Inother embodiments, barrier layer 58 can consist of titanium, zirconiumand nitrogen.

Barrier layer 58, formed in accordance with the present invention, cancomprise non-columnar grains, or both non-columnar and columnar grains.In particular instances, non-columnar grains can be substantiallyequi-axed. In particular instances, barrier layer 58 can have asubstantial absence of amorphous phase material.. Where barrier layer 58comprises both non-columnar and columnar grains, the barrier layer canbe described as having a thickness, a first portion of the thicknesshaving non-columnar grains and a second portion of the thickness havinga columnar grain microstructure. Where both non-columnar and columnarstructures are present in barrier layer 58, the first portion comprisingnon-columnar grains is typically closer to interface 59 than is thesecond portion containing the columnar grain structure. Relativethickness of the first portion and second portion of layer 58 is notlimited to a particular value. Additionally, it is to be understood thatin particular instances a transition region may exist within the secondportion which has both columnar and non-columnar grain structure.

An exemplary layer 58 comprising (TiZr)_(x)N_(z) and having a thicknessgreater than about 5 nm can have a first portion that lacks columnargrain growth, the first portion being within the first 5 nm of interface59, and can comprise a second portion having columnar grains, the secondportion comprising the remaining portion of barrier layer 58 extendingoutward from the first portion. In an alternate example, where layer 58has a thickness of greater than about 10 nm, the first portion thatlacks columnar grains can be within the first 10 nm of interface 59 andthe remaining portion extending outward from the first portion cancomprise columnar grains. In another embodiment where barrier layer 58comprises (TiZr)_(x)N_(z) having a thickness of less than or equal toabout 10 nm, the entire thickness of barrier layer 58 can consist ofnon-columnar grain structure.

Referring still to FIG. 4, a copper-containing seed layer 60 is formedover barrier layer 58. Copper-containing seed layer 60 can comprise, forexample, high purity copper (i.e., copper which is at least 99.995%pure), and can be deposited by, for example, sputter deposition from ahigh purity copper target.

The titanium materials of the present invention can providesubstantially uniform step coverage suitable for lining gap structuressuch as those utilized in copper dual damascene integration.Accordingly, titanium materials according to the present invention canbe utilized where opening 56 has a high aspect ratio, where the aspectratio refers to the ratio of the opening height (a length of sidewall55) relative to the opening width (the length of bottom surface 57).FIG. 5 illustrates the step coverage for an opening having an aspectratio of 4:1 (200 nm wide×800 nm high). The figure shows a(TiZr)_(x)N_(z) barrier liner before (Panel A) and after (Panel B)deposition of the copper seed layer. The substrate utilized in formingthe structure shown in FIG. 5 contains 200 nm wide gap structures etchedin SiO₂. The resulting barrier layer and copper seed layer where eachobserved to be smooth and of uniform thickness.

FIG. 6 illustrates wafer fragment 50 after it has been exposed tochemical-mechanical polishing (CMP) to remove layers 58 and 60 from overan upper surface of insulative material 54 while leaving materials 58and 60 within trench 56. CMP of a (TiZr)_(x)N_(z) layer over a SiO₂coating resulted in a mirror-quality surface finish which, when examinedby SEM showed no discernable scratches on the entire surface of the film(not shown). Additionally, no delamination of the (TiZr)_(x)N_(z) filmoccurred during CMP.

Additional processing that can occur after formation of seed layer 60includes thermal processing. The thermal processing can comprise, forexample, an anneal at a temperature of from about 100° C. to about 300°C., for about 30 minutes, under vacuum. Where the titanium alloycomprises one or more elements having a standard electrode potential ofless than −1.0V, it can be advantageous to expose layer 58 to thermalprocessing in order to diffuse the elements having a standard electrodepotential of less than −1.0V to the barrier interfaces, as discussedabove.

FIG. 7 illustrates wafer fragment 50 at a processing step subsequent tothat of FIG. 6, and specifically shows a copper-based material 70 formedwithin trench 56 (FIG. 6). Copper-based material 70 can be formed by,for example, electrodeposition of copper onto seed layer 60. Anadvantage of having a conductive barrier layer 58 is evidenced in FIG.7. Specifically, as trenches become increasingly smaller, the amount ofthe trench made smaller by barrier layer 58 relative to that consumed bycopper material 70 can increase. Accordingly, layers 58, 60 and 70 canbe considered a conductive component, with layer 58 having anincreasingly larger representative volume as trench sizes becomesmaller. A reason that layer 58 can have an increasingly larger volumeis that there are limits relative to the thickness of layer 58 desiredto maintain suitable copper-diffusion barrier characteristics. As therelative volume of layer 58 increases within the conductive componentcomprising layers 58, 60 and material 70, it can be desired to have goodconductive characteristics within material 58 to retain good conductivecharacteristics within the conductive component.

Barrier layer 58 formed utilizing titanium materials according to thepresent invention allows the resistance contribution of barrier layer 58to be low relative to conventional TaN barrier layers. For example, in acopper filled via having dimensions of 100 nm×100 nm, a 10 nm thickbottom barrier/liner of TaN deposited at 8.6 kW would have a viaresistance contribution from the TaN barrier/liner of approximately 2.54Ω. The corresponding (TiZr)_(x)N_(z) liner having identical dimensionsto the TaN liner would have a via resistance contribution ofapproximately 0.69 Ω. Corresponding liners deposited at 2 kW would havea via resistance contribution of 22.8 Ω for the TaN liner andapproximately 1.06 Ω for the (TiZr)_(x)N_(z) liner.

Materials formed in accordance with the present invention can havesuitable mechanical properties for barrier layer applications. FIG. 8shows that materials formed in accordance with the present invention canhave mechanical properties equal to, or better than, those of 3N5tantalum, with the mechanical properties of FIG. 8 being reported inunits of Ksi (i.e, 1000 lbs/in²).

EXAMPLES

The invention is illustrated by, but not limited to, the followingexamples. The examples describe exemplary methodologies for forming thinfilms comprising various materials encompassed by the present invention.

Example 1

A TiZr target comprising 5.0 at % Zr was reactively sputtered in a N₂/Aratmosphere. The resulting TiZrN thin film had a thickness ofapproximately 20 nm and an electrical resistivity of approximately 125μΩ·cm. Transmission electron microscopy (TEM) examination of the TiZrNfilm showed extremely small crystallites (<5 nm at the SiO₂ interface),which could. not be measured by X-ray, and which were stable aftervacuum annealing at 700° C. for 5 hours. A 150 nm Cu film was thendeposited onto the TiZrN film so that diffusional properties of theTiZrN film could be tested after annealing at high temperature. Resultsindicate that the TiZrN film had good adhesion to intermetallicdielectrics and wetting characteristics with Cu. The thin film hadoverall properties that are adequate for a typical Cu/low-k dielectricprocess. FIG. 9 shows the Rutherford Back-scattering Spectroscopy (RBS)profile of as-deposited Ti_(0.45)zr_(0.024)N_(0.52); and Table 1tabulates various aspects of the data of FIG. 9. FIG. 10 illustratesthat there is no apparent diffusion of Cu into the TiZrN layer aftervacuum annealing at about 450° C.-700° C. for 1 hour. FIG. 11 shows theRBS profile of the TiZrN film after the Cu layer has been stripped fromthe wafer. This figure again shows no apparent diffusion of Cu into theTiZrN layer after 5 hours at 700° C.

Similar studies performed on a TiZr layer (deposited in an absence ofadded nitrogen) indicated a similar absence of copper diffusion afterheat treatment for one hour at 550° C. TABLE 1 RBS determined filmcomposition in atomic percent Thickness Film (nm) Si O Ti N Zr TiZrN  200 0 0.45 0.526 0.024 SiO₂ 300 0.334 0.666 0 0 0 Si wafer 1 0 0 0 0

Example 2

(TiZr)_(x)N_(z) films were deposited by reactive physical vapordeposition (PVD) onto a SiO₂ coated silicon wafer, at a base chamberpressure of approximately. 10⁻⁸ Torr in an Ar/N2 plasma at approximately5 mTorr. Film deposition was performed at a temperature of about 400°C., at a power of about 6.5 kW. RBS analysis indicated that theresulting layer had a Zr to Ti ratio which matched the Zr to Ti ratio ofthe deposition target, and indicated a metal (TiZr) to nitrogen ratio of(TiZr)_(0.47-0.6)N_(0.53-0.04). The variable measurement obtained forthe N content of the (TiZr)_(x)N_(z) layer may possibly be due tofluctuation in the N₂ pressure during the deposition, and mayadditionally reflect resolution limit of the RBS analysis (+5% for N).

For comparison purposes, TaN films were prepared using depositionconditions as set forth above for the (TiZr)_(x)N_(z) layer formation.The amount of N incorporated into the TaN layers was found to be morevaried relative to the (TiZr)_(x)N_(z) layers, with RBS analysisindicating Ta to N ratios of Ta_(0.6-0.4)N_(0.4-0.6). The largervariation in the amount of nitrogen incorporated into the TaN films maypotentially be due to the presence of both amorphous and crystallinephases in the TaN films.

FIG. 12 shows transmission electron microscopy (TEM) comparison betweenthe microstructures of a TaN film (Panel A) and a (TiZr)_(x)N_(z) film(Panel B). The TEM images of (TiZr)_(x)N_(z) layers reveal non-columnarmicrostructure within the fist 10 nm from the SiO₂, with columnar grainsobserved in regions of the layer beyond the first 10 nm from the SiO₂.The non-columnar microstructure comprises thin, equi-axed grains. Thecolumnar microstructure has column diameters in the range of from about10 nm to about 20 nm. Selected area diffraction (SAD) pattern of the(TiZr)_(x)N_(z) columns (Panel B; inset) indicated crystalline materialhaving NaCl (B1) type f.c.c structure.

In contrast, the TEM images of TaN layers indicate smaller grains whichappear to be imbedded as part of a mixture of amorphous and crystallinephase material near the SiO₂ interface. (Additional TaN layers formed atvaried deposition powers (not shown) revealed that the fraction ofamorphous material increases with decreasing deposition power.) Atincreased distance from the SiO₂ interface, the TaN layer containedcolumnar structure having larger column diameters relative to thoseobserved in the (TiZr)_(x)N_(z) layers. The SAD pattern for TaN layers(Panel A; inset) reveals a poorly defined ring indicative of h.c.pcrystal structure.

Example 3

The barrier strength and film stability of (TiZr)xN, layers as thin as 5nm were analyzed. A 5 nm (TiZr)_(x)N_(z) film was formed utilizing thedeposition conditions set forth in Example 2, above. Subsequent to thedeposition of the film layer, copper was deposited over the barrierfilm. Copper deposition was conducted at a temperature of about 350° C.,at a power of 2 kW, in the presence of Ar gas. Chemical vapor depositionwas utilized to deposit a Si₃N₄ capping layer over the copper. RBS (notshown) and TEM analysis revealed no indication of any copper diffusionthrough the 5 nm layer after 1 hour at 650° C. FIG. 13 shows a TEM imageof the microstructure of a cross-section of the 5 nm (TiZr)_(x)N_(z)film after 1 hour at 650° C. There is no indication in this figure ofany copper diffusion or secondary phase formation with copper.

Example 4

Adhesion of (TiZr)_(x)N_(z) layers was also analyzed and compared to TaNlayers. Stud-pull tests were conducted utilizingSi/SiO₂/(TiZr)_(x)N_(z)/Cu/Si₃N₄ stacks and Si/SiO₂/TaN/Cu/Si₃N₄ stacksformed utilizing the conditions set forth in Examples 2 and 3, above.Average stud-pull strength measurements of about 900 MPa were obtainedfor both the (TiZr)_(x)N_(z) and the TaN.

Peel adhesion tests utilizing the Standard Tape Test Method wereconducted to determine (TiZr)_(x)N_(z) adhesion to low-k dielectricmaterials. Stacks were formed as above with the exception that the SiO₂layer was substituted with an approximately 600 nm layer of low-kdielectric material having a k value of less than or equal to about 2.6.Analysis included comparison between stacks having (TiZr)_(x)N_(z)disposed between the copper and the dielectric, and stacks withouthaving a layer interposed between the copper and the dielectric. Theresults of the peel test utilizing three different low-k dielectricmaterials are summarized in Table 2.

The observed adhesion of the (TiZr)_(x)N_(z) to the dielectric materialswas maximal when degassing was conducted prior to deposition of the(TiZr)_(x)N_(z) layer. As shown in Table 2, (TiZr)_(x)N_(z) adheres wellto the tested dielectric materials. TABLE 2 Peel Test Adhesiondielectric/ dielectric/ Dielectric (TiZr)_(x)N_(z) copper Dielectricmaterial type K value interface interface GX-3 Organic 2.6 Pass PassHOSP Inorganic 2.5 No data Pass NANOGLASS ® E Inorganic 2.2 Pass Fail

Example 5

The electrical resistivity of (TiZr)_(x)N_(z) films deposited over arange of deposition power was analyzed and compared to resistivityproperties of TaN films. Both the TaN films and the (TiZr)_(x)N_(z)films were deposited at a deposition temperature of about 400° C. in anAr/N₂ plasma at a deposition gas pressure of from about 2-5 mTorr. Sheetresistance (R_(s)) was measured by the 4point probe method. Bulkelectrical resistivity (ρ=R_(s)t) was determined by measuring the filmthickness (t) using SEM, TEM and profilometery. The specific gravity ofdeposited films was determined from the weight and thickness of thefilm.

FIG. 14 depicts the resistivity values of films as a function ofdeposition powers over a power range of from about 2 kW to about 8.6 kW.Both the TaN and the (TiZr)_(x)N_(z) films exhibited decreasedresistivity with increasing deposition power. However, the resistivityof (TiZr)_(x)N_(z) films was consistently lower than that of TaN filmsdeposited at the corresponding deposition power. Additionally, theresistivity of the (TiZr)_(x)N_(z) varied to a much lesser extentrelative to TaN, with a resistivity of about 106 μΩ·cm at a depositionpower of about 2 kW, and a resistivity of about 69 μΩ·cm for a filmdeposited at about 8.6 kW. The TaN films exhibit increased film densitywith increasing deposition power but contained significant fractions ofamorphous microstructure at the lower end of the range of depositionpower. In contrast, the (TiZr)_(x)N_(z) films had pronounced crystallinestructure and dense atomic packing at all deposition powers.

In addition to the embodiments described above having barrierscomprising a single TiQ or (TiQ)_(x)N_(z) material, barrier layersaccording to the present invention can comprise a combination ofmaterials. For example, for a barrier layer having a thickness, a firstportion of the thickness can comprise a first material and a secondportion of the thickness can comprise a second material. In someapplications the first portion can comprise a first atomic percentnitrogen while the second portion contains a different atomic percentnitrogen, or a substantial absence of nitrogen. The invention alsoencompasses barrier layers having a third portion of the thickness ofthe layer that comprises a third material that differs relative to atleast one of the first and second materials. A difference in nitrogenconcentrations, a range of nitrogen concentrations or a nitrogenconcentration gradient can be incorporated into the barrier layer byappropriately altering the nitrogen atmosphere during deposition of thebarrier layer. A material substantially free of nitrogen can bedeposited utilizing a deposition atmosphere that lacks added nitrogen.

Referring again to FIG. 7, an exemplary barrier layer 58 can be abi-layer having a first portion that comprises TiZr and a second portioncomprising,(TiZr)_(x)N_(z) with x and y having values as describedabove. In particular applications it can be advantageous to providebarrier layer 58 as a bi-layer to enhance or maximize adhesion of thebarrier to the adjacent interface materials such as underlyingnon-metallic material 54 and overlying metallic material 60. TiZr hasenhanced adhesion to materials such as copper materials relative to(TiZr)_(x)N_(z) . However, (TiZr)_(x)N_(z) adheres better toSiO₂ thandoes TiZr. Accordingly, it can be advantageous to provide a barrierbi-layer having a (TiZr)_(x)N_(z) portion adjacent SiO₂ interface 59,and a TiZr portion adjacent the interface between barrier 58 and coppermaterial 60.

The relative thickness of the TiZr portion and the (TiZr)_(x)N_(z)portion of a barrier bi-layer are not limited to any particular value orrange of values. Accordingly, the invention contemplates aTiZr/(TiZr)_(x)N_(z) bi-layer having a TiZr portion of the barrierthickness of from greater than zero % to less than 100%. The inventionsimilarly contemplates all proportional ranges ofTiZr/(TiZr)_(x)N_(z)/TiZr barriers and(TiZr)_(x)N_(z)/TiZr/(TiZr)_(x)N_(z) layers. Where alternative materialsare utilized for material 54 and 60, appropriate barrier materials canbe determined by considering the adhesion properties of the interfacingmaterials, in combination with the resistivity and strength propertiesdesired for the particular barrier application.

It is to be understood that the invention also contemplates barrierlayers comprising combinations of other Ti alloys. Alternativelydescribed, barrier 58 can comprise various combinations and thicknessesof any of the TiQ, (TiQ)_(x)N_(z) and Ti_(x)Q_(y)N_(z)O_(w), materialsset forth above.

The embodiments described herein are exemplary embodiments, and it is tobe understood that the invention encompasses embodiments beyond thosespecifically described. For instance, the chemical-mechanical polishingdescribed as occurring between the steps of FIGS. 4 and 6, could insteadbe conducted after electrodeposition of the copper material 70 that isshown in FIG. 7. Also, the anneal described with reference to FIG. 6could be conducted instead after the processing of FIG. 7.

The titanium alloys of the present invention can be utilized to protectmaterials and surfaces in, for example, microelectronic devices. Theresults of the studies conducted on (TiZr)_(x)N_(z) indicated that(TiZr)_(x)N_(z) can be effectively used as a copper barrier in metalinterconnect technology. Due to the comparable or superior properties of(TiZr)_(x)N_(z) relative to TaN materials, the (TiZr)_(x)N_(z) materialsand films of the present invention may be particularly suitable asalternative to TaN in other microelectronic applications and in othertechnologies as well. Additionally, although various aspects of theinvention are described with reference to creating barrier layers toalleviate copper diffusion, it is to be understood that the methodologydescribed herein can be utilized for creating barrier layers that impedeor prevent diffusion of metals other than copper; such as, for example,Ag, Al, Sn and Mg.

1. A thin film consisting essentially of Zr, N and optionally Ti, atleast a portion of the thin film having a non-columnar grain structure.2. The thin film of claim 1 having a thickness of less than or equal toabout 10 nm.
 3. The thin film of claim 1 having a thickness, wherein afirst portion of the thickness comprises the non-columnar grainstructure and wherein a second portion of the thickness comprisescolumnar grains.
 4. The thin film of claim 3 wherein the columnar grainshave diameters of from about 10 nm to about 20 nm.
 5. The thin film ofclaim 3 wherein the thin film is disposed over a silicon dioxide surfaceand wherein the first portion of the thickness is disposed closer to thesilicon dioxide surface than is the second portion.
 6. The thin film ofclaim 1 having an atomic ratio of Ti to Zr greater than or equal to 1.0.7. The thin film of claim 5 consisting essentially of Ti, Zr and N. 8.The thin film of claim 1 wherein the N is present in the thin film atfrom about 40 atomic percent to about 60 atomic percent.
 9. The thinfilm of claim 1 having a resistivity of from about 69 μΩ·cm to about 106μΩ·cm.
 10. A barrier layer comprising Ti and Zr, a first portion of thebarrier layer comprising a non-columnar grain structure, and a secondportion of the layer comprising columnar grain structure.
 11. Thebarrier layer of claim 10 further comprising one or more elementsselected from the group consisting of Al, Ba, Be, Ca, Ce, Cs, Hf, La,Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P, S, Sm, Gd,Dy, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta.
 12. The barrier layer of claim 10disposed between a metallic material and a non-metallic material. 13.The barrier layer of claim 12 wherein the non-metallic materialcomprises a member of the group consisting of SiO₂ and low-k dielectricmaterials.
 14. The barrier layer of claim 12 wherein the metallic layercomprises copper.
 15. The barrier layer of claim 13 having a thicknessof from about 10 nm to about 20 nm, wherein the first portion of thelayer is closer to the non-metallic material than is the second portion.16. A metal diffusion barrier comprising: a first layer comprising Tiand Q and being substantially nitrogen free, where Q comprises one ormore elements selected from the group consisting of Al, Ba, Be, Ca, Ce,Cs, Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P,S, Sm, Gd, Dy, Ho, Er, Yb, W, Zr, Cr, Mo, Nb, and Ta; and a second layercomprising (TiQ)_(x)N_(z).
 17. The metal diffusion barrier of claim 16wherein Q comprises Zr.
 18. The metal diffusion barrier of claim 16wherein the second layer is over the first layer, and further comprisinga third layer over the second layer, the third layer comprising Ti andZr and being essentially free of nitrogen.
 19. The metal diffusionbarrier of claim 16 wherein the first layer is over the second layer,and further comprising a third layer over the first layer, the thirdlayer comprising (TiQ)_(x)N_(z).
 20. The metal diffusion barrier ofclaim 16 disposed between a metallic material and a non-metallicmaterial.
 21. A copper diffusion barrier comprising a bi-layer, a firstportion of the bi-layer comprising TiZr, and a second portion of thebi-layer comprising (TiZr)_(x)N_(z).
 22. The copper diffusion barrier ofclaim 21 wherein the second portion comprises non-columnar grainstructure.
 23. The copper diffusion barrier of claim 21 wherein thesecond portion is adjacent a layer of silicon dioxide and the firstportion is adjacent a copper based material.
 24. A titanium-comprisingmaterial having an electrical resistivity of from about 69 μΩ·cm toabout 106 μΩ·cm, and having a substantially uniform thickness.
 25. Thetitanium-comprising material of claim 24 further comprising Zr.
 26. Thetitanium-comprising material of claim 25 having an atomic ratio of Ti toZr of greater than or equal to 1, and further comprising from about 40atomic percent to about 60 atomic percent N.
 27. The titanium-comprisingmaterial of claim 24 further comprising N.
 28. A copper barrier filmhaving a first portion comprising a non-columnar grain structure, and asecond portion comprising a columnar grain structure, the film having asubstantial absence of amorphous phase material.
 29. The film of claim28 comprising Ti.
 30. The film of claim 28 comprising Zr.
 31. The filmof claim 28 comprising Ti, Zr and N.
 32. The film of claim 28 consistingessentially of (TiZr)_(x)N_(z), where x=0.40-0.60 and z=0.40-0.60. 33.The film of claim 18 having an electrical resistivity of from about 69μΩ·cm to about 106 μΩ·cm.
 34. The film of claim 28 having a thickness ofless than 20 nm.
 35. A diffusion protected surface comprising: amaterial having a surface; and a thin film consisting essentially of Zrand N and optionally Ti over the surface, at least a portion of the thinfilm having a non-columnar grain structure.
 36. The diffusion protectedsurface of claim 35 wherein the thin film comprises Ti.
 37. Thediffusion protected surface of claim 35 wherein the material having thesurface comprises a non-metallic material.
 38. The diffusion protectedsurface of claim 35 wherein the material having the surface comprisesSiO₂.
 39. The diffusion protected surface of claim 35 wherein the thinfilm is disposed between the surface and a metallic material comprisingone or more of Cu, Ag, Sn, Mg and Al.
 40. A structure comprising: asilicon substrate; a insulative material over the substrate; a barrierlayer consisting essentially of (TiZr)_(x)N_(z) over the insulativematerial, the barrier layer having a substantial absence of amorphousstructure, at least a portion of the barrier layer comprisingnon-columnar grain structure; and a layer comprising a metal over thebarrier layer.
 41. The structure of claim 40 wherein x=0.44-0.60 andz=0.40-0.60.
 42. The structure of claim 40 wherein the metal comprisescopper.
 43. The structure of claim 40 wherein the metal comprisescopper, wherein the insulative material comprises SiO₂; wherein thebarrier layer has a thickness of less than or equal to about 5 nm; andwherein, the barrier layer substantially prevents diffusion of copperfrom the layer comprising the metal into the SiO₂ during heat treatmentof the structure at a temperature of about 650° C. for about 1 hour. 44.The structure of claim 40 wherein the metal comprises copper, whereinthe insulative material comprises SiO₂; wherein the barrier layer has athickness of less than or equal to about 20 nm; and wherein, the barrierlayer substantially prevents diffusion of copper from the layercomprising the metal into the SiO₂ during heat treatment of thestructure at a temperature of about 700° C. for about 5 hours.
 45. Amicroelectronic device comprising: a insulative material comprising anopening having a bottom surface and a sidewall surface; a barrier layerover the bottom surface, the barrier layer comprising Ti and Zr, andhaving an electrical resistivity of less than or equal to about 69 μΩ·cmto about 106 μΩ·cm; and a material comprising copper disposed over thebarrier layer.
 46. The microelectronic device of claim 45 wherein theopening has a width of less than or equal to about 350 nm.
 47. Themicroelectronic device of claim 45 wherein the opening has a width ofless than or equal to about 100 nm.
 48. The microelectronic device ofclaim 45 wherein the barrier layer is disposed over the sidewallsurface.
 49. The microelectronic device of claim 48 wherein the barrierlayer has a substantially uniform thickness over the bottom surface andover the sidewall surface.
 50. The microelectronic device of claim 49wherein the opening has a height to width aspect ratio of greater thanor equal to
 1. 51. The microelectronic device of claim 50 wherein theaspect ratio is greater than
 2. 52. The microelectronic devise of claim49 wherein thickness is less than or equal to about 20 nm.
 53. Themicroelectronic devise of claim 49 wherein thickness is less than orequal to about 5 nm.
 54. The microelectronic devise of claim 45 whereinthe barrier layer comprises an atomic ratio of Ti to Zr of greater thanor equal to 1.0.
 55. The microelectronic devise of claim 45 wherein thebarrier layer further comprises N.
 56. The microelectronic device ofclaim 55 wherein the barrier layer comprises from about 40 atomicpercent to about 60 atomic percent N.
 57. The microelectronic device ofclaim 55 wherein the barrier layer consists essentially of Ti, Zr and N.58. The microelectronic device of claim 55 wherein the barrier layerconsists of Ti, Zr, and N.
 59. The microelectronic device of claim 45wherein the material comprising copper consists essentially of copper.60. A method of forming a barrier layer comprising: providing asubstrate comprising a material to be protected; providing a targetcomprising Ti and Zr; and in the presence of an Ar/N₂ plasma, ablatingmaterial from the target onto the substrate at a deposition power offrom about 2 kW to about 9 kW, the ablating forming a barrier layercomprising Ti, Zr and N and having a substantially uniform thicknessover at least a portion of the material to be protected.
 61. The methodof claim 60 wherein the target consists essentially of Ti and Zr. 62.The method of claim 60 wherein the barrier layer has an atomic ratio ofTi to Zr of greater than or equal to about
 1. 63. The method of claim 60wherein the barrier layer has an electrical resistivity of from about 69μΩ·cm to about 106 μΩ·cm.
 64. The method of claim 60 further comprisingdepositing a conductive material over the barrier layer, the conductivematerial comprising a metal.
 65. A method of forming a microelectronicdevice, comprising: providing a substrate having one or more gapstructures formed in an insulative material; lining the gap structureswith a layer comprising Ti, the layer having a substantially uniformthickness and having an electrical resistivity of from about 69 μΩ·cm toabout 106 μΩ·cm; depositing a copper material over the layer.
 66. Themethod of claim 65 wherein the layer further comprises N and one or moreelements selected from the group consisting of Al, Ba, Be, Ca, Ce, Cs,Hf, La, Mg, Nd, Sc, Sr, Y, Mn, V, Si, Fe, Co, Ni, B, C, La, Pr, P, S,Sm, Gd, Dy, Zr, Ho, Er, Yb, W, Cr, Mo, Nb, and Ta.
 67. The method ofclaim 66 wherein the layer consists essentially of Ti, Zr and N.
 68. Themethod of claim 65 wherein the one or more gap structures compriseopenings having a height to width aspect ratio of greater than or equalto
 4. 69. The method of claim 68 wherein the openings have a width ofless than or equal to about 350 nm.
 70. The method of claim 68 whereinthe openings have a width of less than or equal to about 200 nm.
 71. Themethod of claim 68 wherein the openings have a width of less than orequal to about 100 nm.
 72. The method of claim 65 wherein the insulativematerial comprises SiO₂.
 73. A method of forming a protected surfacecomprising: providing a substrate having a surface into a reactionchamber; providing a target within the reaction chamber, the targetconsisting essentially of Ti and Zr; ablating material from the targetonto the surface in the presence of nitrogen to deposit a first layerover the surface; and ablating material from the target in an absence ofadded nitrogen to form a second layer over the first layer.
 74. Themethod of claim 73 wherein the surface comprises silicon dioxide. 75.The method of claim 73 wherein the first layer has a thickness of lessthan or equal to about 10 nm, and has a microstructure consistingessentially of non-columnar grains.
 76. The method of claim 73 whereinthe first layer has a thickness of greater than about 10 nm, andcomprises a first portion having non-columnar grain structure and asecond portion comprising columnar grain structure.